iridoids and Metabolic-Syndrome

Olive (Olea europaea Linn., Fam. Oleaceae) is commonly known as Zaytoon in Mediterranean region. Its fruits and oil are essential components of Mediterranean diets. Olive tree is a prevalent plant species and one of the important cultivated crops of Mediterranean region. Oleuropein is a phenolic constituents of olive, which, along with its related compounds, has been indicated to be majorly responsible for its beneficial effects. Oleuropein is a secoiridoid type of phenolic compound and consists of three structural subunits: hydroxytyrosol, elenolic acid, and a glucose molecule. It is also reported to be the chemotaxonomic marker of olive. The oleuropein is reported to possess a number of biological activities including action against dyslipidemia, antiobesity, antidiabetic, antioxidant, antiatherogenic, antihypertensive, antiinflammatory, and hepatoprotective actions. The scientific evidence supports the role of oleuropein as a potential agent against metabolic syndrome. The present review discusses chemistry of oleuropein along with potential role of oleuropein with reference to pathophysiology of metabolic syndrome.

Topics: Adolescent; Adult; Antioxidants; Humans; Iridoid Glucosides; Iridoids; Metabolic Syndrome; Young Adult

Topics: Adipokines; Animals; Anthocyanins; Aorta; Atherosclerosis; Cardiovascular Diseases; Cholesterol, Dietary; Cornus; Humans; Iridoids; Liver; Liver X Receptors; Male; Metabolic Syndrome; Obesity; Plant Extracts; PPAR alpha; PPAR gamma; Rabbits; Triglycerides

Accumulation of visceral fat induces various symptoms of metabolic syndrome such as insulin resistance and abnormal glucose/lipid metabolism and eventually leads to the onset of ischemic cerebrovascular diseases. Geniposide, which is iridoid glycoside from the fruit of Gardenia jasminoides ELLIS, is recognized as being useful against hyperlipidemia and fatty liver. In order to clarify the effect of geniposide on metabolic disease-based visceral fat accumulation and the relevant molecular mechanism, experiments were performed in spontaneously obese Type 2 diabetic TSOD mice and the free fatty acid-treated HepG2 cells. In the TSOD mice, geniposide showed suppression of body weight and visceral fat accumulation, alleviation of abnormal lipid metabolism and suppression of intrahepatic lipid accumulation. In addition, geniposide alleviated abnormal glucose tolerance and hyperinsulinemia, suggesting that geniposide has an insulin resistance-alleviating effect. Next, in order to investigate the direct effect of geniposide on the liver, the effect on the free fatty acid-treated HepG2 fatty liver model was investigated using genipin, which is the aglycone portion of geniposide. Genipin suppressed the intracellular lipid accumulation caused by the free fatty acid treatment and also significantly increased the intracellular expression of a fatty acid oxidation-related gene (peroxisomal proliferator-activated receptor: PPARα). From these results, it was confirmed that geniposide has an anti-obesity effect, an insulin resistance-alleviating effect and an abnormal lipid metabolism-alleviating effect, and the metabolite genipin shows a direct effect on the liver, inducing expression of a lipid metabolism-related gene as one of its molecular mechanisms.

Topics: Adipose Tissue; Animals; Anti-Obesity Agents; Body Weight; Diabetes Mellitus, Type 2; Drug Evaluation, Preclinical; Fatty Acids, Nonesterified; Fatty Liver; Gardenia; Glucose Intolerance; Hep G2 Cells; Humans; Hyperinsulinism; Hypoglycemic Agents; Insulin Resistance; Iridoids; Lipid Metabolism; Liver; Male; Metabolic Diseases; Metabolic Syndrome; Mice; Mice, Obese; Obesity; Phytotherapy; Plant Preparations